U. PITTSBURGH (US) — Transfused blood may need to be stored in a different way to prevent the breakdown of red blood cells that can lead to complications, including infection, organ failure, and even death.

Researchers at the University of Pittsburgh and Wake Forest University reported those findings this week in the early online version of Circulation. The results are from the team’s ongoing exploration of the interaction between red blood cell breakdown products and nitric oxide (NO). The work points to new biological mechanisms that can reduce blood flow and possibly damage vital tissues after administration of blood that has been stored for longer than 39 days.

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In recent years, doctors have noted that transfusions of either many units of blood or of blood stored a long time may be associated with a greater frequency of complications, such as increased infection risk; kidney, lung, or multi-organ failure; and death, particularly among medically vulnerable patients, says senior investigator Mark Gladwin, chief of the Division of Pulmonary, Allergy and Critical Care Medicine at the University of Pittsburgh.

“When blood sits for a while, some of the cells break down and release their contents, which include molecules of hemoglobin and red blood cell microparticles,” he says. “These accumulate in the stored bag of blood and are transfused into the patient with the blood. In the bloodstream, the hemoglobin and microparticles bind to and destroy NO, a very important molecule that is used by the body to keep blood vessels dilated for normal blood flow.”

The scavenging of NO causes blood vessel constriction that can prevent tissues and organs from getting adequate oxygen and activate the platelets and the coagulation system, as well as cause inflammation, Gladwin says.

From their experiments, he and his Wake Forest collaborators found that human blood stored under standard conditions accumulated “free” hemoglobin that was no longer contained in a cell and microparticles of damaged cells. Those breakdown products reacted with NO about 1,000 times more quickly than did intact red blood cells. Also, transfusion of even very low concentrations of hemoglobin caused blood vessel constriction and hypertension in a rat model.

“Avoiding the storage lesion, as it is referred to in our field, could require a new approach to how donor blood is stored prior to transfusion,” says senior author Daniel Kim-Shapiro, professor of physics at Wake Forest.

“Transfusion of stored blood is one of the most common medical therapies,” he says. “By understanding the mechanism of the storage lesion, we can design methods to make blood transfusion safer. For example, perhaps we can restore nitric oxide activity that is lost upon transfusion, use preservation solutions that better limit the degradation of blood cells, or develop agents that scavenge free hemoglobin.”

Other research projects are under way to find approaches to correct the problem, and to assess the safety of blood for transfusion that has been stored for longer than 14 days. Currently, federal guidelines allow transfusion of blood that has been stored for up to 42 days.

The study was funded by the National Institutes of Health, the Institute for Transfusion Medicine, and the Hemophilia Center of Western Pennsylvania.